Ducts, Grilles, & Air

<body topmargin=0 leftmargin=0 marginheight=0 marginwidth=0> <table cellpadding=0 cellspacing=0 border=0><tr> <td valign="top" rowspan="2" width=159 style="border-right: 1px solid #000000;" BGCOLOR="#000033" TEXT="#F7F7FF" background="77cc8c83.gif"> <div> <B> <object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://active.macromedia.com/flash4/cabs/swflash.cab#version=4,0,0,0" id="airswish1bresize" width="110" height="103"> <param name="movie" value="HTMLobj-1913/airswish1bresize.swf"> <param name="quality" value="high"> <param name="wmode" value="transparent"> <param name="bgcolor" value="#DDDDDD"> <embed name="airswish1bresize" src="HTMLobj-1913/airswish1bresize.swf" quality="high" wmode="transparent" bgcolor="#DDDDDD" width="110" height="103" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash"> </embed> </object>  </B></div> <div> <B> <STYLE>  </STYLE>  </B></div> <div> <B> <IMG SRC="30b1e150.png" border=0 width="30" height="21" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">  </B><A HREF="id35_m.htm#top_of_page" TARGET="TRLX_Middle" TITLE="Ducts, Grilles, Air"><B>Top of Page</B></A></div> <div> <B> <TABLE BORDER="0" CELLPADDING="2" CELLSPACING="1" WIDTH="134" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP HEIGHT= 27 ><NOBR><div> <B><IMG SRC="30b1e150.png" border=0 width="30" height="21" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">  </B><A HREF="id35_m.htm#various_types_of_ducts_used_for" TARGET="TRLX_Middle" TITLE="Ducts, Grilles, Air"><B>Duct pictures</B></A></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 27 ><NOBR><div> <B><IMG SRC="30b1e150.png" border=0 width="30" height="21" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"> </B><A HREF="id35_m.htm#_insulation_for_ducts" TARGET="TRLX_Middle" TITLE="Ducts, Grilles, Air"><B> Insulation</B></A></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 27 WIDTH="128"><div> <B><IMG SRC="30b1e150.png" border=0 width="30" height="21" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">  </B><A HREF="id35_m.htm#duct_size" TARGET="TRLX_Middle" TITLE="Ducts, Grilles, Air"><B>Size </B></A></div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 27 WIDTH="128"><div> <B><IMG SRC="30b1e150.png" border=0 width="30" height="21" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">  </B><A HREF="id35_m.htm#grilles_____" TARGET="TRLX_Middle" TITLE="Ducts, Grilles, Air"><B>Grilles</B></A></div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 27 WIDTH="128"><div> <B><IMG SRC="30b1e150.png" border=0 width="30" height="21" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">  </B><A HREF="id35_m.htm#filters" TARGET="TRLX_Middle" TITLE="Ducts, Grilles, Air"><B>Filters</B></A></div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 27 ><NOBR><div> <B><IMG SRC="30b1e150.png" border=0 width="30" height="21" ALIGN="BOTTOM" HSPACE="0" VSPACE="0">  </B><A HREF="id35_m.htm#what_to_ask" TARGET="TRLX_Middle" TITLE="Ducts, Grilles, Air"><B>What to ask</B></A></div> </NOBR></tD> </tR> </TABLE></B></div> <bR> </td> <td valign="top" colspan=2 height=85 style=" border-bottom: 1px solid #000000;" BGCOLOR="#000000" TEXT="#F7F7FF" background="77cc8ca1dvldtc.gif"> <div> <B>  Ducts - Grilles - Filters - Air</B></div> <div> </div> </td> </tr><tr> <td valign="top" height=395 width="100%" colspan=2 BGCOLOR="#FFFBF0" TEXT="#080000" background="67d96963.jpg"> <div>  <A NAME="top_of_page"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A><FONT SIZE="4" COLOR="#000033" FACE="Arial" ><B>Air and Air handling is as important as a heat exchanger or compressor. In spite of its extreme importance and simplicity it confounds many. </B></FONT></div> <div> Air handling is the simplest major part of an air conditioning system. The cooling of air is complexed with a refrigerant circuit, compressor-condenser, several electric circuits, and control devices. Heating usually involves a heat exchanger, fuel, and it's handling, combustion, controls, and again electric circuits. </div> <div> <I><B>But look at the simplicity of a fan, ducts, and diffusers, (air carrying components ). </B></I></div> <bR> <div> <B>Air carrying ducts. </B></div> <div> The furnace, air handler, or package unit, has a fan motor in their units and that fan motors job is to "pump" air and the correct volume of air at the designed restriction. The volume of air it pumps is extremely important and that's why some of the important considerations are the type of fitting, where the location may be, size of duct as well as fitting size, and many other factors that a trained professional is aware of for supply & returns. The inside of all air carrying devices should be free from dirt, mold, and water. This circulation of supply & return air is a sealed system but if any of these are detected then contact an airconditioning specialist to see where the problem may be but it's not going away on it's own.</div> <div> The correct amount of air is transported (supply air) to each grille to each conditioned room via ducts, pipes, some means of getting the air to the room (conditioned area). Then that air must get back to the unit (return air).  That <B>supply & return air circulation</B> if not hindered will help in your comfort and that's what you really want. </div> <div> <B>For air conditioning</B> the heat is removed (via return air) and by the units evaporator coil,  then blown into the areas via room supply air grilles (located in the ceiling, floor, or walls).  By this heat removal & lowering of it's temperature, humidity / moisture is increased at the coil  and that's why the correct unit size and the correct duct size is very important to get these results. The air blows out of the grilles at somewhere around 62 degrees but it's humidity is around 95% to 100%. <I><B><U>Surprising isn't it.</U></B></I>  Think about it. When the air's temperature is reduced to a certain temperature then moisture starts extracting. Air blown out of the grilles and mixed with the room's air give the results. In high humidity areas it is very important to size a unit correctly otherwise too large of a unit can create moisture / mildew problems.</div> <div> <B>For heating </B>the return air is heated by the units furnace and/or heatpump coil, and/or electrice heat strips & it is blown into the room via the supply grilles (supply air). The heated air can create a "too dry" condition and sometimes water is needed to be put into this air so the humidity can be at a comfortable level.  That's one of the reasons of a humidifier. Again the correct duct size is very important to achieve your comfort level.</div> <div> Make sure your home has been correctly calculated for the proper size of unit, (<U> </U><I><U>load calculation using Manual "J"</U></I><U> </U>of ACCA ),and the ducts have been sized and installed for the correct air deliverance to each room, ( <I><U>Manual "D"</U></I> of ACCA). </div> <div> A new "addition" may "ROB" from the system and may play havoc with your comfort ( <I>if not calculated for the addition and checked to see if the existing unit is large enough for the new set of criteria, Heating and Air conditioning</I> ). <B>Now the unit may be too small and the ducts may not be the correct size to handle this new addition ( existing units should not be over sized by 15% of the sensible air conditioning load for air conditioning ).</B> A professionally trained person can tell you what you have for the old part, what will be needed for the new part and whether the existing system will handle the new requirement and if the ducts need to be changed.</div> <div> <B><U>The complete air volume circulated is important to your comfort. Anything less or restricted could affect your comfort.</U></B></div> <div> The comfortable air recommended is 4 to 6 air changes of air per hour be it airconditioning for sure but as close to that for heating as well. That's all the cubic volume of conditioned air to pass thru the unit 10 to 15 minutes. If circulation is less than that then air may be stale & stagnant.  Your fuel / utility bill or consumption can be affected by this.</div> <div> A good measurement of air needed is 30 cfm per cooling BTU. Example: The "Heat gain" (air conditioning load) was calculated to be 3000 BTU for a given room divide by 30 therefore the air requirement is 100 cfm (cubic feet per minute of air) placed into that room. </div> <div> Ducts, connections, floor joist and wall studs that may be used, extractors (those things that may be placed in a duct system can hurt air flow as well as help air flow) trunks & branches are sized to <B>deliver and return the correct amount of air, (cfm), to reach your comfort. </B> </div> <div> Ducts are connected (put together) in a lot of ways. It depends on the type or material of the duct. You also should ask your installing contractor how they do their connections and also check or verify that with the local code enforcement building department. </div> <DIV ALIGN="LEFT"></DIV> <div>  <A NAME="various_types_of_ducts_used_for"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A><FONT SIZE="3" COLOR="#000000" FACE="Arial" >Various types of "ducts".used for heating / air conditioning.</FONT></div> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="554" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="COLS" HSPACE="0" VSPACE="0" BGCOLOR=#FFFFFF > <tR> <tD VALIGN=TOP BGCOLOR=#CC99CC HEIGHT= 191 ><NOBR><div> <IMG SRC="2d2afb60.png" border=0 width="175" height="182" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#FFFFFF><NOBR><div> <IMG SRC="2d4a9b90.png" border=0 width="169" height="185" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#000033><NOBR><div> <IMG SRC="2d6ad850.png" border=0 width="173" height="133" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 ><NOBR><div>  Metal spiral round </div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> Metal round snap lock </div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> Fiberglass R4-R6-R8</div> </NOBR></tD> </tR> </TABLE></div> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="542" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="COLS" HSPACE="0" VSPACE="0" BGCOLOR=#FFFFFF > <tR> <tD VALIGN=TOP BGCOLOR=#FFFFFF HEIGHT= 154 ><NOBR><div> <IMG SRC="2dcb8800.png" border=0 width="184" height="128" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#FFFFFF><NOBR><div> <IMG SRC="2d9a4900.png" border=0 width="164" height="144" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#FFFFFF WIDTH="176"><div> <IMG SRC="2db5a940.png" border=0 width="90" height="148" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="168"><div> Metal uninsulated</div> </tD> <tD VALIGN=TOP WIDTH="172"><div> Flex R4-R6-R8</div> </tD> <tD VALIGN=TOP WIDTH="176"><div> Aluminum </div> </tD> </tR> </TABLE></div> <bR> <bR> <div>  <A NAME="_insulation_for_ducts"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A> <FONT SIZE="3" COLOR="#000000" FACE="Arial" >Insulation for metal ducts</FONT></div> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="425" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="COLS" HSPACE="0" VSPACE="0" BGCOLOR=#FFFFFF > <tR> <tD VALIGN=TOP BGCOLOR=#000000 HEIGHT= 171 ><NOBR><div> <IMG SRC="144c8a50.png" border=0 width="200" height="165" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#66334C><NOBR><div> <IMG SRC="145c8a50.png" border=0 width="200" height="165" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 ><NOBR><div> Exterior wrap insulation</div> </NOBR></tD> <tD VALIGN=TOP><NOBR><div> Interior liner insulation</div> </NOBR></tD> </tR> </TABLE></div> <div> and some duct connectors</div> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="318" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="COLS" HSPACE="0" VSPACE="0" BGCOLOR=#FFFFFF > <tR> <tD VALIGN=TOP BGCOLOR=#888888 HEIGHT= 227 ><NOBR><div> <IMG SRC="2e127dd0.png" border=0 width="295" height="221" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="306"><div> Grille & duct connectors</div> </tD> </tR> </TABLE></div> <bR> <div> <B>Insulation on heating or air conditioning ducts primarily do several things. </B></div> <div> 1. It helps in your loss or gain of any heat in the ducts. In other words it helps in the utility consumption & your comfort. That is what you pay for in the unit's operation cost and the unit's capacity. </div> <div> 2. For air conditioning it prevents the condensation or sweating than can occur from those ducts.</div> <div> If leaks occur then loss of efficiency & / or sweating can happen. Also when wrap insulation is pulled too tight it to loses it's R value (it's insulating value). The higher R value the better is your insulation but a cost effective factor comes into play. It really isn't cost effective to increase to the extremes. </div> <div> Usually insulation for ducts is R4 or R6 with the more common R6 being used in the insulation value. A formula used in insulation is: The actual attic air temperature minus the inside duct air temperature & then divide that result by 15. Ex: 125 degree in attic less 60 degree air inside ac duct = 65degrees  then divide by 15 = R 4.3 </div> <div> Insulating attics & walls are not included in this discussion but are in "Air Conditioning Survey & Estimates" and other pages on this Website.</div> <div>  <A NAME="duct_size"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> It is important that ducts are <B>sized</B> & <B>connected</B> correctly. One may have a measured run of 45 feet but the fittings, turns, effective length, type of duct, all must be taken in consideration and the actual run is 110feet ("effective length due to these considerations"). Some installers use "Duct sizing calculators" but the shown static's are for a length of 100 feet. If your system exceeds that then different static may be required but also the fans static may not deliver the air required. There is a limitation on the fans ability to pump air (remember all the fan does is pump air). The more <B>restriction could amount to less air</B> from the fan that's delivered to each of your conditioned rooms. </div> <div> Duct dimensions or sizes are inside measurements & you have to add for any insulation. Ex: a 8" round duct is 8" inside but if insulation is 1" then 10" outside measurements. All ducts even rectangle inside to outside insulation you have to add for the thickness of the insulation to the inside dimension of the duct. Don't forget to add for two sides. This dimension can become critical in tight spaces & if the duct or insulation is mashed then you lose the insulating value & sweating & some loss of efficiency could occur. Some codes will require  an extra piece of insulation between the support & the duct for this reason.</div> <div> A source that dealers use is ACCA's <I><B>( Air Conditioning Contractor's Association ) </B></I>Manual "D"<FONT SIZE="3" COLOR="#0000FF" FACE="Arial" > <A HREF="http://www.accaconference.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=ACCOA&Product_Code=29-D&Category_Code=M"; Target="_blank" TARGET="_top" TITLE="http://www.accaconference.com/Merchant2/">Manual D site click here</A>.</FONT> There are a lot of rules that determine the correct size, fitting, & connections. Some are resistance, static pressure, effective length, & more but you as a home owner do not need to know all things that determine size. When the ac dealer  takes the time to learn these procedures the duct system should be installed properly. <I><B><U>Always ask if they are using Manual "D" procedures for the duct system.</U></B></I></div> <DIV ALIGN="LEFT"></DIV> <div> A layout of some work to be done may be helpful.</div> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="556" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="NONE" HSPACE="0" VSPACE="0" BGCOLOR=#FFFBF0 > <tR> <tD VALIGN=TOP BGCOLOR=#FFFBF0 HEIGHT= 287 ><NOBR><div> <IMG SRC="2e4900f0.png" border=0 width="400" height="271" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#FFFBF0 WIDTH="123"><div> Ducts are shown as white lines with grilles shown as red. The trunk is from the unit & shown as left then right. Branch lines are those to each grille. Those <U>trunks,</U>  <U>branch</U> lines & <U>grilles</U>, are sized according to the volume of air they carry & sizes are shown.</div> </tD> </tR> <tR> <tD VALIGN=TOP COLSPAN=2 HEIGHT= 38 ><NOBR><div> Duct systems are shown (drawn plan) normally as a trunk, outlet branches,  </div> <div> grilles, (supply & return) with units & their locations.</div> </NOBR></tD> </tR> </TABLE></div> <div> Local Building Departments may require a complete working layout much like the above but with dimensions & locations of all that will be done. The AC contractor should have a layout so they can pull a permit & comply with local codes and so the installers will have a plan to go by. <I>Even on replacements graph paper could be an answer to installers & the home owner.</I> </div> <div> Those additions to be added on now or later can present a problem especially in humid areas. Let's say the old home & the new addition has a load calculated. The unit will be oversized until the addition is completed. Sometimes the addition is never done then the unit is now over sized. That not only cost you more money but the humidity may be to much resulting in your discomfort. </div> <div> Also you don't add or extend a branch duct to accommodate a new addition. Remember the branch line was originally sized for it's air volume only. <B><U>Not the extra air needed by the add on</U></B>.</div> <div> When walls / floors are used for 2nd floors, returns, supplies, many reasons usually unsatisfactory results happen. To try to cure this problem is probably futile. So be aware and a certified dealer in Manual D procedures will hopefully place you in good hands.</div> <div> All units will have a "Spec data" that will say what the unit will do at certain resistance (static pressure). Resistance can come from many sources such as duct sizes, duct connections, filters & types, items in a duct such as extractors & turning vanes, grilles, and those things that affect the air in flowing & returning.</div> <DIV ALIGN="LEFT"></DIV> <div> Below is a sample of a "Spec sheet".</div> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="427" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP BGCOLOR=#FFFFFF HEIGHT= 286 ><NOBR><div> <IMG SRC="2e690160.jpg" border=0 width="400" height="278" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> </TABLE></div> <div> So the size of ducts, where & how they are connected all play a part in your comfort.</div> <div> <IMG SRC="7ed195e0.jpg" border=0 width="793" height="350" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> <div> This particular example is .10 static at 300 cfm thru the duct that carries the air and shows a 9" inside pipe.</div> <div>  For residential a duct calculator using .10 for duct sizing has been very successful.</div> <div>  <A NAME="grilles_____"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> Grilles.... </div> <div> Whether they are ceiling, floor, wall, where ever they are located their function is to provide a proper supply air disbursement to each area. A comparison is like putting your thumb over a garden hose, the volume of water is the same but it throws it further. Grilles do just that. Usually the air comes from the grille at 500 feet per minute, throws 2/3 of the distance & then their velocity is down to 50 FPM. That's provided drafts are not experienced. To small of a grille can cause the drafts.</div> <div> If grilles are located in a ceiling then the installer should see if the roof truss, piping, electrical, and other things that might prohibit a center &/or chosen location. It's good practice to mention to the home owner two selected locations but a lot depends on what may or may not be in the way. Ceiling supply grilles should blow along the ceiling to an outside wall.  <U>It is very important that the air blown out the grilles covers and mixes with the air in the room. (not 1/2 the room but all of it or unsatisfactory results may occur.)</U></div> <div> Floor grilles especially supplies should be located to blow up the exterior wall. The furniture location may be critical with floor diffusers or returns. Any obstacles that may prohibit the correct disbursement of air.</div> <div> Just think of your home as all the heat comes in or goes out from the exterior perimeter and mixture of the units air with this fact is where your comfort could very well lie.</div> <div>  Returns are usually located by the unit & the thermostat. Again size can be of the utmost concern. There are a lot of grilles & choices but a good quality grille does differ from the cheaper grille. Depending on your climate return grilles are sometimes located no more than 50 feet apart and that is primarily to prevent any stratification of air, (cold feet). Some require this rule before they will approve the installation.</div> <div> It is equally important that all the air in the room is returned to the unit for conditioning then sent back via the supply grilles. When the return air is restricted then once again unsatisfactory results will probably occur. <U>The full air circulation is part of the key for satisfactory results. Remember you are asking for comfort (not nuts & bolts in the </U>system).</div> <div> If a room is not cold or warm enough then there is not the correct amount of air being delivered. There could be many reasons for this and the 1st thing I look for is the size of duct delivering and returning the air. There are other reasons but a trained professional can evaluate the installation and conservation.  </div> <div> The complete circulation which encompasses many things, (duct sizing, connection, & other), is important in having your comfort.</div> <div> A good AC contractor and his/her using good practices will assure you of getting a good job.</div> <DIV ALIGN="LEFT"></DIV> <div>  <B>Below are some grilles</B></div> <bR> <div> <B>One criteria for selecting supplies and return grilles is the effective area ( the free area of the grille). Those louvers and cross bars take up space or the free area. When a grille is selected the free area of a particular grille must come into play. When incorrectly selected the end results could be drafts, not enough air, meaning loss of obtaining your comfort. </B></div> <div> <B>Manufacturer's of grilles differ but will have the free area, air throw, amount of air shown for the proper selection. Those "cheaper" grilles may affect your comfort level. That is one of the ways a job price can be made cheaper is by using material that is cheaper and may be inferior. Try to stay with "quality" material.</B></div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="571" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="COLS" HSPACE="0" VSPACE="0" BGCOLOR=#FFFFFF > <tR> <tD VALIGN=TOP BGCOLOR=#FFFFFF HEIGHT= 150 ><NOBR><div> <IMG SRC="2e72c660.png" border=0 width="300" height="102" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> <tD VALIGN=TOP BGCOLOR=#FFFFFF><NOBR><div> <IMG SRC="2e9f06c0.png" border=0 width="240" height="108" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="307"><div> Ceiling supply</div> </tD> <tD VALIGN=TOP WIDTH="245"><div> Returns</div> </tD> </tR> </TABLE></div> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="432" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="NONE" HSPACE="0" VSPACE="0" BGCOLOR=#FFFFFF > <tR> <tD VALIGN=TOP BGCOLOR=#FFFFFF HEIGHT= 99 ><NOBR><div> <IMG SRC="2ea905d0.png" border=0 width="400" height="93" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> <tR> <tD VALIGN=TOP HEIGHT= 19 WIDTH="420"><div>  Supply wall grilles</div> </tD> </tR> </TABLE></div> <bR> <bR> <div> So you as the home owner need to be aware of those unwanted drafts, cold feet, & other improperly sized & placed return grilles. FHA required a return grille to be no more than 50 ft otherwise another return would be required. Return air has to get back to the unit. The installer should make provisions for this.</div> <bR> <div>  <A NAME="filters"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A></div> <div> Filters</div> <div>                  Whether they are located in the grille or unit <B>they need to filter & clean the air as much as possible.</B> Remember filters only filter the air borne particles & they only filter as good as their filter media. </div> <bR> <div> <B>The most common benchmarks for air cleaning performance </B>are the Atmospheric Dust Spot Test and the Synthetic Dust Weight Arrestance Test as specified by ASHRAE Standard 52-76. There are other test methods but the results they produce can mislead anyone who isn't a professional engineer.</div> <bR> <div> <B>Atmospheric Dust Spot Test:</B></div> <div> Atmospheric (outdoor) air is pumped into a test duct. Upstream & downstream of the test filter, samples of the air are captured in high-efficiency, laboratory-grade filters, leaving "dust spot" stains on the filters.</div> <bR> <div> <B>Synthetic Dust Weight Arrestance:</B></div> <div> In this test an air cleaner is mounted in a clean test duct into which is fed a measured weight of synthetic dust. The synthetic dust is a blend of bulk test dust that resembles vacuum cleaner sweepings but is made to exacting ASHRAE specifications.</div> <div> An efficient filter paper is carefully weighed then mounted downstream to catch particles that get through the air cleaner. The filter paper is weighed again after the test to establish an air cleaning rating.</div> <bR> <div> <I><B>Removing smells or odors is primarily done by using a charcoal insert with the filter. Normal filters without the charcoal insert will probably not effectively remove odors or smells. </B></I></div> <bR> <div> When getting a filter see what you would like to have it remove & how much money you are willing to spend to get the result</div> <div> Filters will remove "microns" & the type of filter will or will not remove these particulates. A dot from a pencil is approximately 10 microns.</div> <bR> <DIV ALIGN="LEFT"></DIV> <div> <TABLE BORDER="2" CELLPADDING="1" CELLSPACING="1" WIDTH="444" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ROWS" HSPACE="0" VSPACE="0" BGCOLOR=#FFFFCC > <tR> <tD VALIGN=CENTER COLSPAN=2 BGCOLOR=#0000CC HEIGHT= 20 WIDTH="432"><div> <B>       ITEM                                                SIZE</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>POLLEN</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>10 - 90 microns</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>MOLD SPORES</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>3 - 100 microns</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>PLANT SPORES</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>10 - 30 microns</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>DUST MITES FECES</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>.1 - 5 microns</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>ANIMAL DANDER</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>15 - 90 microns</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>HOUSEHOLD DUST</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>5 - 90 microns</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>LINT</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>10 - 90 microns</B></div> </tD> </tR> <tR> <tD VALIGN=CENTER HEIGHT= 20 WIDTH="250"><div> <B>BACTERIA</B></div> </tD> <tD VALIGN=CENTER WIDTH="181"><div> <B>.3 - 15 microns</B></div> </tD> </tR> </TABLE></div> <bR> <div> Those 50 cent filters don't do that great of a job but it's probably more psychological to the home owner. Certainly cheaper. </div> <div> I have seen some filters that have open spaces in them that will allow much of the particles to go by (filter by pass). Air will follow the path of least resistance. A 1/8" gap is completely unforgivable. </div> <bR> <div> <TABLE BORDER="2" CELLPADDING="2" CELLSPACING="1" WIDTH="199" BORDERCOLORLIGHT="#C0C0C0" BORDERCOLORDARK="#808080" FRAME="BOX" RULES="ALL" ALIGN="LEFT" HSPACE="0" VSPACE="0" > <tR> <tD VALIGN=TOP BGCOLOR=#FFFFFF HEIGHT= 206 ><NOBR><div> <IMG SRC="34da3c80.gif" border=0 width="163" height="200" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></div> </NOBR></tD> </tR> </TABLE></div> <div> Recommended filter air velocities should be no more that 500 Feet per minute or less but many times filter air velocities are much higher and that is unfortunate.</div> <div> Filter people have known a long time that a filter can't filter air with velocities high enough to rifle dust particles straight thru the filter. Velocities over 500 FPM can cause dust that is caught to vibrate off & into the occupied space. Such a design is very wrong. Anything you can do to increase the filter area, thus <B>reducing velocity thru the filter, will help in having a cleaner home. Also it should result in a quiet air flow.</B></div> <bR> <div> There are certain types of filters that should not be used in residential homes due to their excessive restriction that could affect your unit performance & maybe result in higher utility consumption.</div> <bR> <div> <B> </B><B>Air delivery is really hindered with some filters, so be wise & be careful. Have your comfort & enjoy it to.</B></div> <bR> <div> There are filters that do a good job of filtering and they usually cost more than those doing a poor job. There are permanent / washable to throw away filters, Hepa, electrostatic, electronic, those with charcoal inserts, & others.</div> <bR> <div> Go to my page "Links & Sites"  for good information & sources of filters. <A NAME="what_to_ask"><IMG BORDER="0" SRC="1x1.gif" HEIGHT="1" ALIGN="bottom" WIDTH="1" HSPACE="0" VSPACE="0" ></A> </div> <bR> <div> You are not buying engineering but your comfort. Any problems & conditions the ac company should & needs to be aware of. They should bear responsibility on their shoulders.</div> <bR> <div> <I><B>Before spending a few thousand dollars & your home is either new construction or existing ask & have written in your contract, duct will or is in accordance with ACCA's ( Air Conditioning Contractor's Association ) Manual "D"..</B></I></div> <bR> <div> <I><B>1. Existing ducts seem to be OK & comply with Manual "D".or</B></I></div> <div> <I><B>2. New ducts will be installed according to Manual "D"</B></I></div> <div> <I><B>and the volume of air from each grille will assure my comfort at design temperatures & </B></I><FONT SIZE="3" COLOR="#000099" FACE="Arial" ><I><B>The company's guarantee that these conditions will be met.</B></I></FONT></div> <div>  <STYLE>  </STYLE>  </div> <bR> <DIV ALIGN="LEFT"></DIV> <div> Always qualify your ac dealer !</div> <bR> <div> <A HREF="id36.htm" TARGET="_top" TITLE="MENU"><IMG SRC="73080200.jpg" border=0 width="128" height="32" ALIGN="BOTTOM" HSPACE="0" VSPACE="0"></A></div> <bR> <bR> <bR> <bR> <bR> <bR> </td> </tr></table></body>